The red, or haemopoietic, bone marrow is a semi-liquid organ, of about 5 liters capacity and contained in the bones. The marrow manufactures the cells which subsequently circulate in the blood after having passed into the "circulating sector", i.e. the blood volume available in the veins and arteries.
For several decades "bone marrow punctures" or "medullary punctures" have been performed in order to remove a sample of haemopoietic marrow required for the conduct of biological examinations. These examinations are required, in particular, by haematologists in cases of serious abnormalities of blood cells, primarily in cases of leukaemias, which are medullary diseases. The equipment used is, in general, specifically designed for this type of puncture, essentially because, on the one hand, of the semi-liquid nature of the organ sampled, the marrow, and, on the other, of the need to reach the marrow by passing through another, hard organ, the bone. Only the bone marrow presents these two characteristics.
The equipment usually includes trocars capable of passing through the sternum, from which comes the name, very frequently used, of sternal puncture. In France, a Mallarme trocar is usually chosen, one which can be pushed manually through the bone. The internal diameter of this trocar varies from 8 to 20 hundreths of a millimetre and its length is sufficient to pass through the thickness of the hard bone (about 1 cm)--or "compact"--which surrounds the marrow. One speaks of passing through the cortex to reach the medullar. Once the bevelled end of the trocar is located in the medullary space, it is necessary to aspirate gently with a syringe in order to withdraw 0.5 to 2.0 ml of marrow; the latter is, in fact, quite viscous and the medullary space is septated into many spaces by quite fragile lamella of bone.
The marrow is collected in a syringe, in the presence of an anticoagulant in order to avoid the formation of a clot. Subsequently, both syringe and trocar are withdrawn. Only the trocar is cleaned, sterilised and reused. From the syringe a drop of marrow is deposited on a slide. The drop is spread, dried and sent to the laboratory where it will be dyed and examined under a microscope.
A result of carrying out what has just been described is that the sampling of marrow constitutes a traumatic experience for the patient. To this major disadvantage, unavoidable to this day, is added the frequently encountered difficulty of the reproducibility of sampling.
The aim of the invention is to remedy these difficulties, at least in part, and, in particular, to provide sampling equipment for bone marrow which will be both less traumatising for the patients and more reliable in the hands of the physician or technician, and at a price reduced to the point where it becomes "disposable", thus eliminating all the problems of sterilisation which, at present, has to be repeated between successive uses of the equipment.